Fannie Mae to crack down on 'strategic defaulters'

This just in from the L.A. Times:

The mortgage giant plans to go to court against those who can afford to make their payments but decide it's not worth it. It also will limit their access to future loans.

And how big a problem are we talking about?

Last March, 31% of foreclosures were described as strategic by the borrowers themselves, compared with 22% in March 2009, researchers at the University of Chicago and Northwestern University reported.

I wonder if they will go after people who've already walked away from their homes.